This is more of curious question as everyone has their own types, and ideas. Some use rucksacks, others choose purses or saddle bags. I'm interested to see who uses what. I myself have a Maxpedition Vulture II that is about 2800 cu inch in the car and when I travel via plane and then a Mountainsmith 3.0 circuit that is close to 6,000 cu in. which is my expedition one.